| With the development of “One Belt,One Road” strategy,infrastructure construction and road network planning,the construction experience of tunnels under the sea is becoming more and more mature.The construction of underwater shield tunnels has become the first choice for traffic development in developed water areas.Due to the existence of a stable supply water source,during the excavation of the underwater shield tunnel,the stress field and the seepage field interact and interact with each other.The change of the stress causes the pore pressure of the tunnel surrounding rock to change,and the pore pressure.The change causes the ground stress to be redistributed,which is easy to cause deformation or instability of the surrounding rock of the tunnel,resulting in engineering accidents.In this paper,the Shuangtai West Street-Da Nanmen Station of Taiyuan Metro Line 2 is under the background of the Yingze Lake section tunnel.The theoretical analysis and numerical simulation are taken as the main research methods to explore the distribution law of seepage field during shield construction.And lining tube sheet water pressure characteristics.The researchcontents mainly include:(1)The basic theory of seepage field-stress field coupling is introduced,and the definite solution conditions and initial conditions for seepage field-stress field coupling are derived.(2)Based on the theory of fluid-solid coupling,taking the section of the Yingtai Lake section of the Shuangtai West Street-Dananmen Station of Taiyuan Metro Line 2 as the engineering background,a three-dimensional fluid-solid coupling numerical model is established by using FLAC3 D to study the stress field of surrounding rock in the construction process of shield tunnel.Distribution of stress field,displacement field,seepage field,formation deformation distribution law and the stress characteristics of lining segment,etc.(3)Research on the variation of seepage field and lining water pressure during the construction of shield tunnel under different head pressures,and the influence of head pressure on the surrounding rock seepage field and lining segment structure during construction period.(4)Combining the Taiyuan West Street-Da Nanmen Station of Taiyuan Metro Line 2,the tunnel construction project of Yingze Lake Section proposed waterproof construction technology and measures.The research conclusions mainly include:(1)Stress field:During the whole process of earth pressure balance shield double-track tunneling,the maximum vertical effective stress is about 4.24 MPa,which is located at the arch of the tunnel.The maximum effective stress in thehorizontal direction is about 3.61 MPa,which is located on both sides of the tunnel in the horizontal direction.In terms of seepage field:after the excavation of the left line tunnel,a pore pressure distribution similar to the "precipitation funnel" is formed around the tunnel,when the right-line tunnel After the excavation is completed,a “double funnel”-like pore pressure distribution is formed around the tunnel;in terms of displacement field:with the excavation of the shield tunnel,the vertical displacement and horizontal displacement of the surrounding rock increase and gradually stabilize.24.09 Mm,25.28mm;with the increase of formation depth,the vertical deformation curve of the formation transitions from a single settlement tank to an asymmetric "double peak" characteristic curve,and the maximum settlement deformation of the formation is about 21.29mm;below the tunnel,along the depth of the formation The increase of the vertical deformation curve of the formation transitions from the asymmetric "double peak" characteristic curve to the single settlement groove curve,and the maximum uplift deformation of the formation is about 23.78 mm.(2)When the head pressure is larger,the pore water pressure of the surrounding rock also increases,and the hydraulic gradient changes on both sides of the tunnel arch waist are particularly significant.During the construction process,the water pressure changes on both sides of the tunnel arch should be monitored.The vertical displacement and horizontal displacement of the segment increase with the increase of the head pressure,but the horizontal displacement of the lining segment is not significantly increased.The verticaldisplacement mainly occurs in the vault and the arch of the lining segment.The horizontal displacement mainly occurs in the horizontal displacement.The two waists of the lining segment converge from side to side;under different head pressures,the stress state of the lining segments after the left and right tunnels are sequentially excavated presents different distribution rules,and the compressive stress of the lining segments increases with the pressure of the head.The increase of the tensile stress of the lining segment is not significant under the pressure of each head;the pore water pressure at the bottom of the arch of the lining segment is greater than the pore water pressure on both sides of the arch waist,and the pore water on the inner surface of the lining segment The pressure is less than the pore water pressure on the outer surface,and the pore water pressure of the lining segments is larger.(3)Waterproof construction technology and measures for interval tunnel engineering include:self-waterproof of lining segments(prevention measures for segment breakage,patch repair),waterproof joints for lining segments(water seal for elastic gasket,waterproof for caulking and hand hole seal)Blocking,node waterproofing),tube sheet waterproofing(synchronized grouting,secondary grouting),tunnel interface waterproofing,etc. |
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